Before being selected to replace Peter Davison as the Doctor, Tom Baker was an established television actor, his most notable role having been that of Paul Merroney in The Brothers. He also guest starred as "Bayban the Butcher" in an episode of Blake's 7.

After appearing in For Maddie with Love, Colin Baker made his first appearance in Doctor Who as Commander Maxil in the story Arc of Infinity. His performance as Maxil was described by producer John Nathan-Turner as being "quite arch" and a little sassy. Despite this, Colin Baker's character became one of the few characters to actually shoot the Doctor, then played by Peter Davison.

When he was officially cast as Davison's successor, he became the only "Doctor" actor to have appeared in the television series as another character, prior to taking on the leading role (On audio, David Tennant has appeared in several Big Finish Doctor Who plays, including Medicinal Purposes with Colin prior to appearing as the Doctor on television in 2005). Ironically, when Colin was cast to replace Davison, many fans cited that shooting scene in Arc of Infinity. Thus prompting Colin to jokingly say that he got the part of the Doctor by killing the incumbent. Colin also stated that he was of no relation to Tom Baker, who played the Fourth Doctor in Doctor Who for seven years.

Colin Baker's first appearance as the Doctor occurred at the final minutes of The Caves of Androzani, where he delivered his first few lines. The closing title sequence for episode four featured his face instead of Peter Davison, and credits him as the Doctor before Davison's own credit. This was the first (and, to date, only) time that the new lead received top billing in the final story of an outgoing Doctor. Colin Baker then made his first full story debut the following week in The Twin Dilemma. It was the first time since 1966 that a new leading actor's debut story was shown before the conclusion of the previous lead's season.

Colin Baker's era was interrupted by a long hiatus, officially because the show was moved back from the spring to the autumn schedule. The Controller of BBC One at the time, Michael Grade, criticised Doctor Who, saying that the programme had become overly violent and its storylines farcical.

Ultimately, Colin Baker was dismissed from the part at the insistence of BBC management, who wanted to refresh the show. Thus he became (and remains) the only actor to be "fired" from the role of the Doctor. With only eleven stories and just short of three years as the incumbent Doctor, Colin Baker remained the "current Doctor" for the shortest time (until Christopher Eccleston in 2005) and he had the least amount of screen time in the role (until Paul McGann in 1996).

Since leaving Doctor Who he has continued to act, mainly on the stage. He played the Doctor once again in the 1993 charity special Dimensions in Time. He also played a Doctor-like character in the BBV video series The Stranger, as well as a standalone BBV drama entitled The Airzone Solution, and has reprised the role of the Doctor in a series of audio plays produced by Big Finish Productions. The audio plays are generally well received by fans, who have suggested that it was bad writing that his Doctor's era suffered from, and not a lack of ability on Colin Baker's part. In a poll conducted by Doctor Who Magazine, fans voted Colin Baker the "greatest" of the Doctors in the audio plays.

Later television work during the 1990s included guest appearances in the BBC's medical drama Casualty, Channel 4's adaptation of A Dance to the Music of Time and as himself as the resident celebrity in 'Dictionary Corner' on the daytime quiz show Countdown, also on Channel 4. He appeared in the first episode of Jonathan Creek (1997). In 1994, Colin Baker became the first (and so far only) Doctor to write a published Doctor Who story, The Age of Chaos, a graphic novel published by Marvel UK featuring the Sixth Doctor and Frobisher.

After the death of his son Jack in 1983, Colin Baker became active in raising the profile of Sudden Infant Death Syndrome research, and is the current chairman of the Foundation for the Study of Infant Deaths. He also appeared in opera, starring in the Carl Rosa Company's production of H.M.S. Pinafore in the principal comedian's role of Sir Joseph Porter, K.C.B.

Colin Baker's most recent role is that of Caldo Inman in the Big Finish Productions audio drama Earthsearch Mindwarp, based on a James Follett novel, broadcast on the digital radio station BBC 7.

Colin Baker has been writing a regular column for his local newspaper, the Bucks Free Press since 1995.

Film and TV

"Doctor Who" (33 episodes)
Arc of Infinity: Part 1 (3 January 1983) - Commander Maxil
The Caves of Androzani: Part 4 (16 March 1984) - The Doctor
The Twin Dilemma: Part 1 (22 March 1984) - The Doctor
The Twin Dilemma: Part 2 (23 March 1984) - The Doctor
The Twin Dilemma: Part 3 (29 March 1984) - The Doctor
The Twin Dilemma: Part 4 (30 March 1984) - The Doctor

Attack of the Cybermen: Part 1 (5 January 1985) - The Doctor
Attack of the Cybermen: Part 2 (12 January 1985) - The Doctor
Vengeance on Varos: Part 1 (19 January 1985) - The Doctor
Vengeance on Varos: Part 2 (26 January 1985) - The Doctor
The Mark of the Rani: Part 1 (2 February 1985) - The Doctor
The Mark of the Rani: Part 2 (9 February 1985) - The Doctor
The Two Doctors: Part 1 (16 February 1985) - The Doctor
The Two Doctors: Part 2 (23 February 1985) - The Doctor
The Two Doctors: Part 3 (2 March 1985) - The Doctor
Timelash: Part 1 (9 March 1985) - The Doctor
Timelash: Part 2 (16 March 1985) - The Doctor

Revelation of the Daleks: Part 1 (23 March 1985) - The Doctor
Revelation of the Daleks: Part 2 (30 March 1985) - The Doctor

The Trial of a Time Lord: Part 1 (6 September 1986) - The Doctor
The Trial of a Time Lord: Part 2 (13 September 1986) - The Doctor
The Trial of a Time Lord: Part 3 (20 September 1986) - The Doctor
The Trial of a Time Lord: Part 4 (27 September 1986) - The Doctor
The Trial of a Time Lord: Part 5 (4 October 1986) - The Doctor
The Trial of a Time Lord: Part 6 (11 October 1986) - The Doctor
The Trial of a Time Lord: Part 7 (18 October 1986) - The Doctor
The Trial of a Time Lord: Part 8 (25 October 1986) - The Doctor
The Trial of a Time Lord: Part 9 (1 November 1986) - The Doctor
The Trial of a Time Lord: Part 10 (8 November 1986) - The Doctor
The Trial of a Time Lord: Part 11 (15 November 1986) - The Doctor
The Trial of a Time Lord: Part 12 (22 November 1986) - The Doctor
The Trial of a Time Lord: Part 13 (29 November 1986) - The Doctor
The Trial of a Time Lord: Part 14 (6 December 1986) - The Doctor

"Doctors" .... Charles Dillon / ... (2 episodes, 2001-2006)
- Honourable Gentlemen (2006) TV Episode .... Charles Dillon
- A Matter of Principle (2001) TV Episode .... Jack Howard
"The Afternoon Play" .... Judge (1 episode, 2006)
- Your Mother Should Know (2006) TV Episode .... Judge
D'Artagnan et les trois mousquetaires (2005) .... Rutaford
"The Impressionable Jon Culshaw" .... Mr. Allen (1 episode, 2004)
- Episode #1.2 (2004) TV Episode .... Mr. Allen
"Time Gentlemen Please" .... Dr. Baker (1 episode, 2000)
- Day of the Trivheads (2000) TV Episode .... Dr. Baker
"Hollyoaks" .... The Judge (1 episode, 2000)

The Asylum (2000) .... Arbuthnot
TravelWise (2000) (V)
"Dangerfield" .... Vicar (1 episode, 1999)
- Haunted (1999) TV Episode .... Vicar
The Waiting Time (1999) (TV) .... Giles Fleming
"Sunburn" .... John Buchanan (1 episode, 1999)
- Episode #1.2 (1999) TV Episode .... John Buchanan
Soul's Ark (1999) (V) .... Galico
"Casualty" .... Colin Miles / ... (2 episodes, 1989-1998)
- An Eye for an Eye (1998) TV Episode .... David Vincent
- Accidents Happen (1989) TV Episode .... Colin Miles
Destiny of the Doctors (1998) (VG) (voice) .... The Doctor
"The Bill" .... William Guthrie (1 episode, 1997)
- Going Down (1997) TV Episode .... William Guthrie
"A Dance to the Music of Time" (1997) (mini) TV Series .... Canon Fenneau (segment film four)
"Jonathan Creek" .... Hedley Shale (1 episode, 1997)
- The Wrestler's Tomb (1997) TV Episode .... Hedley Shale
"The Knock" .... Desmond Dewhurst (1 episode, 1997)
- Episode #3.4 (1997) TV Episode .... Desmond Dewhurst
"The Famous Five" .... Fake Mr. Brent (2 episodes)
... aka Enid Blyton's Famous Five (International: English title: complete title)
- Five Go to Billycock Hill: Part 1 (????) TV Episode .... Fake Mr. Brent
- Five Go to Billycock Hill: Part 2 (????) TV Episode .... Fake Mr. Brent
The Harpist (1997) .... Father Rupitsch
... aka Harfenspielerin, Die (Germany)
"Tellystack" (1997) TV Series
Eye of the Beholder (1995) (V) .... The Stranger/Soloman
... aka Stranger VI (UK: video box title)
Breach of the Peace (1994) (V) .... The Stranger/Soloman
... aka The Stranger: Breach of the Peace (UK: complete title)
The Stranger: The Terror Game (1994) (V) .... The Stranger/Soloman
... aka The Terror Game (UK: short title)
The Zero Imperative (1994) (V) .... Russell
... aka P.R.O.B.E.: The Zero Imperative (UK: reissue title)
... aka The Stranger: The Zero Imperative (UK: video box title)
Doctor Who: Dimensions in Time (1993) (TV) .... The Doctor
"The Young Indiana Jones Chronicles" .... Harry George Chauvel (1 episode, 1993)
- Palestine, October 1917 (1993) TV Episode .... Harry George Chauvel
The Airzone Solution (1993) (V) .... Arnold Davies
The Stranger: In Memory Alone (1993) (V) .... The Stranger
... aka In Memory Alone (International: English title)
The Adventures of Young Indiana Jones: Daredevils of the Desert (1992) (V) .... Maj. Gen. Harry George Chauvel
More Than a Messiah (1992) .... The Stranger
... aka The Stranger: More Than a Messiah (International: English title)
Summoned by Shadows (1992) .... The Stranger
... aka The Stranger: Summoned by Shadows
Cybermen: The Early Years (1992) (V) .... Presenter
Myth Makers Vol. 19: Colin Baker (1989) (V)
"Jim'll Fix It" .... The Doctor (1 episode, 1985)
- Episode dated 23 February 1985 (1985) TV Episode .... The Doctor
Swallows and Amazons Forever!: The Big Six (1984) (TV) .... Dr. Dudgeon
Swallows and Amazons Forever!: Coot Club (1984) (TV) .... Dr. Dudgeon
"The Citadel" (1983) (mini) TV Series .... Vaughn
"Juliet Bravo" .... Frankie Miller (1 episode, 1982)
- The Intruder (1982) TV Episode .... Frankie Miller
Dangerous Davies - The Last Detective (1981) .... William Lind
"For Maddie with Love" (1980) TV Series
"Blakes 7" .... Bayban (1 episode, 1980)
- City at the Edge of the World (1980) TV Episode .... Bayban

"The Brothers" .... Paul Merroney (44 episodes, 1974-1976)
- The Christmas Party (1976) TV Episode .... Paul Merroney
- The Ordeal (1976) TV Episode .... Paul Merroney
- The Knock on the Door (1976) TV Episode .... Paul Merroney
- Out of the Blue (1976) TV Episode .... Paul Merroney
- The Golden Road (1976) TV Episode .... Paul Merroney
(39 more)
"The Carnforth Practice" .... Bob Anderson (1 episode, 1974)
- Undue Influence (1974) TV Episode .... Bob Anderson
"Fall of Eagles" (1974) (mini) TV Series .... Crown Prince Willie
"Great Mysteries" .... Barclay (1 episode, 1973)
... aka Orson Welles' Great Mysteries
- A Terribly Strange Bed (1973) TV Episode .... Barclay
"War & Peace" (1972) (mini) TV Series .... Anatole Kuragin
"The Moonstone" (1972) (mini) TV Series .... Maj. Frayne
"The Edwardians" (1972) (mini) TV Series .... Joseph Laycock
"Public Eye" .... Town Hall Clerk (1 episode, 1971)
- The Man Who Didn't Eat Sweets (1971) TV Episode .... Town Hall Clerk
"Cousin Bette" (1971) (mini) TV Series .... Count Wenceslas Steinbock
"Roads to Freedom" .... Claude (2 episodes, 1970)
- The Reprieve: Part 3 (1970) TV Episode .... Claude
- The Age of Reason: Part 6 (1970) TV Episode .... Claude
"The Adventures of Don Quick" .... Rebel (1 episode, 1970)
- People Isn't Everything (1970) TV Episode .... Rebel